This invention relates generally to semiconductor wafer shaping, and more particularly to semiconductor wafer polishers for polishing the faces of semiconductor wafers.
The final step in a conventional semiconductor wafer shaping process is a polishing step to produce a highly reflective and damage-free surface on one face, and sometimes both faces, of the semiconductor wafer. Polishing of the wafer is accomplished by a mechanochemical process in which a rotating polishing pad rubs a polishing slurry against the wafer. The slurry includes fine silica particles (mechanical action) suspended in an alkali solution (chemical action).
Semiconductor electronic devices are fabricated from polished semiconductor wafers. The requirement for geometrical tolerance of the polished wafer has become more stringent as the complexity of device design has increased. Microscopic device geometries require each wafer to have a predetermined uniform thickness and to have at least one face which deviates less than one micrometer from the highest point to the lowest point when the wafer is held on a flat vacuum chuck.